A bifunctional polymer-based ammonia adsorbent and a method for preparing the same

Abstract

The application discloses a kind of dual-functional polymer-based ammonia adsorbent and preparation method thereof, which can efficiently adsorb low-concentration ammonia.The application is prepared by the following steps: first, quaternary ammonium reaction of vinyl imidazole and functional halogenated alkane, then chelation reaction of metal chloride, so that the product is dual-functional, then free radical copolymerization reaction of di-vinyl benzene, to obtain dual-functional polymer-based ammonia adsorbent with porous structure.The obtained polymer-based adsorbent contains weak acidic group and metal ion, and has ultra-high adsorption capacity for low-concentration ammonia (adsorption capacity for 3 vol.% ammonia can be as high as 10.8 mol / kg), and excellent regeneration performance and ammonia adsorption selectivity.The dual-functional polymer of the application has high adjustability of functional groups, and has good industrial application potential.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of new chemical materials, and particularly relates to a bifunctional polymer-based ammonia adsorbent and a preparation method thereof. BACKGROUND

[0002] Ammonia is considered as one of the most important and valuable products in the global chemical industry, which is widely used in the production of valuable agricultural fertilizers, pharmaceuticals, organic compounds and polymer compounds. In addition, ammonia is also regarded as a hydrogen source and applied in the field of hydrogen energy engineering. Although some progress has been made in the alternative production of ammonia, the production of most ammonia still mainly adopts the traditional Haber-Bosh process. The process mainly utilizes the reaction of nitrogen and hydrogen at high pressure to generate ammonia. However, due to the limitation of reaction thermodynamic equilibrium, the conversion rate of ammonia synthesis reaction is only 10-20%. Usually, the synthesized ammonia is collected by physical cooling liquefaction. However, limited by the vapor-liquid equilibrium of ammonia, about 3% of ammonia will remain in the circulating gas, which will lead to the reduction of ammonia synthesis efficiency and affect the ammonia production capacity. Therefore, it is necessary to recover the part of low-concentration ammonia.

[0003] In addition, due to the wide application of ammonia, more than 10 million tons of ammonia is discharged into the atmosphere as industrial waste every year. The ammonia concentration in these waste gases usually varies from 450 ppm to 30000 ppm. Since ammonia is the most abundant alkaline gas in the atmosphere, it has strong corrosiveness. Therefore, a large amount of low-concentration ammonia is discharged into the atmosphere, causing serious environmental pollution. Worse still, ammonia can react with acidic oxides (such as sulfur and nitrogen oxides) to generate solid particles less than 2.5 μm, thereby becoming the precursor of PM 2.5 in the atmosphere, causing serious damage to the environment. Therefore, it is of great importance to capture and recover low-concentration ammonia for environmental protection and economic development.

[0004] For the separation of ammonia by absorption, there are two main methods, i.e. liquid absorption method and solid adsorption method. In the liquid absorption method, liquid absorbents are mainly used to capture ammonia. Ionic liquids (ILs) and deep eutectic solvents (DESs) as emerging environmentally friendly liquid absorbents have attracted widespread attention. ILs and DESs have many excellent characteristics, such as wide liquid range, low volatility, flexible structural designability, etc. There are also many reports on the application of ILs and DESs in ammonia separation. However, the ionic nature of ILs and DESs makes them have high viscosity, and the practical application of ILs and DESs is also greatly limited. In contrast, the solid adsorption method does not have such a problem, because the solid adsorbent is usually fixed in two parallel towers for adsorption and regeneration in turn. In addition, compared with the liquid absorption method, the solid adsorption method usually requires lower regeneration energy input. SUMMARY

[0005] To solve the problem of insufficient adsorption capacity of low-concentration ammonia gas caused by the existing solid adsorbent due to the reasons such as fewer types of functional sites and lower density, the present application provides a bifunctional polymer-based ammonia adsorbent with high ammonia adsorption capacity (especially for low-concentration ammonia), good regeneration, high selectivity, containing multiple functional sites and high density of functional sites.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] A bifunctional polymer-based ammonia adsorbent, whose chemical structural formula is as follows:

[0008] ,

[0009] Among them, X is one of YCl3, Y2Cl5 and Y3Cl7, Y is one of Co, Ni, Zn, Fe, Mn, Mg, Ca, Sn and Cu; R is one of OH, NH3 and COOH; a≥10, b≥10. + Cl − .

[0010] The preparation method of the bifunctional polymer-based ammonia adsorbent is to first carry out quaternary ammonium reaction of vinyl imidazole and functionalized halogenated alkane, then introduce metal chloride to carry out chelation reaction to realize bifunctionalization, and then introduce divinylbenzene to carry out free radical copolymerization reaction to obtain the bifunctional polymer-based ammonia adsorbent with porous structure; which includes the following steps:

[0011] 1) Mix vinyl imidazole and functionalized halogenated alkane, then add organic solvent a, under the protection of inert gas, after reflux reaction, wash the obtained mixture with organic solvent b, dry the washed product to obtain intermediate product 1; the reaction formula is as follows:

[0012] ;

[0013] 2) Mix intermediate product 1 and metal chloride, add organic solvent c to react, then spin the obtained reaction liquid at a certain temperature, dry the product after spinning to obtain intermediate product 2; the reaction formula is as follows:

[0014] ;

[0015] 3) Mix intermediate product 2 with divinylbenzene and azobisisobutyronitrile, add aqueous solution of tetrahydrofuran, stir for a certain time at room temperature, then put the polytetrafluoroethylene liner containing the mixed solution into an autoclave and place it in an oven to react at a certain temperature; after the reaction is completed, the obtained product is placed at room temperature to volatilize, then dry the volatilized product to obtain the bifunctional polymer-based ammonia adsorbent; the reaction formula is as follows:

[0016] .

[0017] Further, in step 1), the molar ratio of the vinyl imidazole to the functional halogenated hydrocarbon is 1:0.5-4; the functional halogenated hydrocarbon is one of 3-chloro-1-propanol, 3-chloropropylamine hydrochloride and 3-chloropropionic acid; the organic solvent a is one of N,N-dimethylformamide, toluene and acetonitrile; the reaction temperature is 60-150 ℃, and the reaction time is 12-60 h; the organic solvent b is diethyl ether or ethyl acetate; and the drying temperature is 20-120 ℃, and the drying time is 12-60 h.

[0018] Further, in step 2), the molar ratio of the intermediate product 1 to the metal chloride is 1:0.5-6; the metal chloride is one of CoCl2, CaCl2, MgCl2, ZnCl2, NiCl2, SnCl2, CuCl2, MnCl2 and FeCl2; the organic solvent c is one of ethanol, dimethyl sulfoxide and methanol; the reaction temperature is 60-80 ℃, and the reaction time is 2-12 h; the rotary evaporation temperature is 30-80 ℃; and the drying temperature is 60-120 ℃, and the drying time is 12-60 h.

[0019] Further, in step 3), the mass ratio of the intermediate product 2, di-vinylbenzene and azobisisobutyronitrile is 1:(0.5-5):(0.005-0.2); the volume ratio of tetrahydrofuran to water in the aqueous tetrahydrofuran solution is 1:1; the stirring time at room temperature is 1-5 h; the reaction temperature is 80-160 ℃, and the reaction time is 12-48 h; the volatilization time is 12-48 h; and the drying temperature is 40-120 ℃, and the drying time is 12-60 h.

[0020] The bifunctional polymer-based ammonia adsorbent can be used for efficient adsorption and separation of low-concentration ammonia.

[0021] Further, the adsorption temperature for ammonia adsorption and separation is -30-40 ℃, and the adsorption pressure is 0.01-5 MPa. The adsorbent after adsorbing ammonia can be regenerated by heating and decompression, the desorption temperature is 60-160 ℃, and the desorption pressure is 0-0.01 MPa.

[0022] The present application has the following advantages:

[0023] (1) The functional groups of the bifunctional polymer-based ammonia adsorbent obtained by the present application are adjustable, and various Lewis acids and metal ions can be introduced as ammonia adsorption sites.

[0024] (2) The obtained bifunctional polymer-based ammonia adsorbent has ultra-high ammonia adsorption capacity for low-concentration ammonia, and the adsorption capacity for 3 vol.% ammonia is as high as 10.8 mol / kg.

[0025] (3) The ammonia adsorbent has excellent regeneration performance and high ammonia selectivity, and has good industrial application potential. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 SEM images of the adsorbent B (1) obtained in Example 2 and the adsorbent D (2) obtained in Example 4.

[0027] Figure 2 The selective adsorption curve of the adsorbent B obtained in Example 2 at 25 ℃ for a ternary mixed gas (3 vol.% ammonia / nitrogen / hydrogen).

[0028] Figure 3 The ammonia cycle performance test results of the adsorbent B obtained in Example 2 at 40 ℃ and 1 bar. DETAILED DESCRIPTION

[0029] A preparation method of a bifunctional polymer-based ammonia adsorbent, comprising the following steps:

[0030] 1) mixing vinyl imidazole and functional halogenated hydrocarbon at a molar ratio of 1:0.5-4, then adding organic solvent a, refluxing at 60-150 ℃ under inert gas protection for 12-60 h, then washing the obtained mixture with organic solvent b, and drying the washed product at 20-120 ℃ for 12-60 h to obtain intermediate product 1;

[0031] 2) mixing intermediate product 1 with metal chloride at a molar ratio of 1:0.5-6, adding organic solvent c, and reacting at 60-80 ℃ for 2-12 h, then rotary evaporating the obtained reaction liquid at 30-80 ℃, and drying the rotary evaporated product at 60-120 ℃ for 12-60 h to obtain intermediate product 2;

[0032] 3) mixing intermediate product 2 with divinylbenzene and azobisisobutyronitrile at a mass ratio of 1:(0.5-5):(0.005-0.2), adding tetrahydrofuran and water at a volume ratio of 1:1, stirring at room temperature for 1-5 h, then loading the mixed solution into a polytetrafluoroethylene liner in a hydrothermal kettle and placing the kettle in an oven, and reacting at 80-160 ℃ for 12-48 h; after the reaction is completed, placing the obtained product at room temperature for volatilization for 12-48 h, and drying the volatilized product at 40-120 ℃ for 12-60 h to obtain the bifunctional polymer-based ammonia adsorbent.

[0033] The functional halogenated hydrocarbon in step 1) is one of 3-chloro-1-propanol, 3-chloropropylamine hydrochloride and 3-chloropropionic acid; the organic solvent a is one of N,N-dimethylformamide, toluene and acetonitrile; and the organic solvent b is diethyl ether or ethyl acetate.

[0034] The metal chloride in step 2) is one of CoCl2, CaCl2, MgCl2, ZnCl2, NiCl2, SnCl2, CuCl2, MnCl2 and FeCl2; and the organic solvent c is one of ethanol, dimethyl sulfoxide and methanol.

[0035] In order to make the content of the application more convenient to understand, the technical solutions of the application will be further described below in combination with specific embodiments, but the application is not limited thereto.

[0036] Example 1

[0037] The vinyl imidazole (0.05 mol, 4.81 g) and 3-chloropropionic acid (0.075 mol, 8.22 g) were weighed into a flask, and 100 mL of acetonitrile was added. Under the protection of inert gas Ar, the temperature was raised to 80 ℃ and the reaction was stirred for 30 h. After the reaction was completed, the obtained mixture was washed with ethyl acetate for 5 times to remove the unreacted raw materials. Finally, the washed product was dried in a 80 ℃ vacuum drying oven for 24 h to obtain [CPA-Vim][Cl].

[0038] [CPA-Vim][Cl] (0.015 mol, 3.04 g) and CoCl2 (0.03 mol, 3.90 g) were taken into a flask, and 30 mL of ethanol was added. The reaction was carried out at 80 ℃ for 2 h. After the reaction was completed, the product was rotary evaporated at 60 ℃, and then the rotary evaporated product was dried in a 80 ℃ vacuum drying oven for 24 h to obtain the product [CPA-Vim][Co2Cl5].

[0039] [CPA-Vim][Co2Cl5] 1 g, divinylbenzene 3 g and azobisisobutyronitrile 0.07 g were respectively taken into a polytetrafluoroethylene liner, and 25 mL of tetrahydrofuran and water in a volume ratio of 1:1 were added. After the mixed solution was stirred at room temperature for 3 h, the polytetrafluoroethylene liner containing the mixed solution was loaded into an autoclave, and then the autoclave was placed in a 120 ℃ oven for reaction for 24 h. After the reaction was completed, the obtained product was left to volatilize at room temperature for 24 h, and then was dried in a 80 ℃ vacuum drying oven for 24 h to obtain a bifunctional polymer-based ammonia adsorbent, which was recorded as adsorbent A.

[0040] Example 2

[0041] Take 3-chloropropylamine hydrochloride (0.06 mol, 7.96 g) and vinyl imidazole (0.05 mol, 4.81 g) in a flask, add 50 mL of N,N-dimethylformamide. Under the protection of inert gas Ar, heat to 70 ℃ and stir for 48 h. After the reaction is completed, the obtained mixture is washed with ether for 5 times to remove the unreacted raw materials. Finally, the washed product is placed in a 80 ℃ vacuum drying oven for drying for 24 h to obtain [Chpy-Vim][Cl].

[0042] Take [Chpy-Vim][Cl] (0.015 mol, 3.36 g) and NiCl2 (0.045 mol, 6.27 g) in a flask, add 30 mL of ethanol, and react at 80 ℃ for 2 h. After the reaction is completed, the product is rotary evaporated at 60 ℃, and then the rotary evaporated product is placed in a 80 ℃ vacuum drying oven for drying for 24 h to obtain the product [Chpy-Vim][Ni3Cl7].

[0043] Take 4 g of [Chpy-Vim][Ni3Cl7], 3 g of divinylbenzene, and 0.06 g of azobisisobutyronitrile in a polytetrafluoroethylene liner, add 25 mL of tetrahydrofuran and water in a volume ratio of 1:1. Stir the mixed solution at room temperature for 3 h, then put the polytetrafluoroethylene liner containing the mixed solution into an autoclave, and then place it in a 120 ℃ oven for reaction for 24 h. After the reaction is completed, the obtained product is placed at room temperature for volatilization for 24 h, and then placed in a 80 ℃ vacuum drying oven for drying for 24 h to obtain a bifunctional polymer-based ammonia adsorbent, which is recorded as adsorbent B.

[0044] Example 3

[0045] Take 3-chloropropylamine hydrochloride (0.06 mol, 7.96 g) and vinyl imidazole (0.05 mol, 4.81 g) in a flask, add 50 mL of N,N-dimethylformamide. Under the protection of inert gas Ar, heat to 70 ℃ and stir for 48 h. After the reaction is completed, the obtained mixture is washed with ether for 5 times to remove the unreacted raw materials. Finally, the washed product is placed in a 80 ℃ vacuum drying oven for drying for 24 h to obtain [Chpy-Vim][Cl].

[0046] Take [Chpy-Vim][Cl] (0.02 mol, 3.77 g) and ZnCl2 (0.02 mol, 2.73 g) in a flask, add 30 mL of methanol, and react at 80 ℃ for 2 h. After the reaction is completed, the product is rotary evaporated at 60 ℃, and then the rotary evaporated product is placed in a 80 ℃ vacuum drying oven for drying for 24 h to obtain the product [Hpro-Vim][ZnCl3].

[0047] Take [Hpro-Vim][ZnCl3] 2 g, divinylbenzene 3 g, azobisisobutyronitrile 0.065 g into a polytetrafluoroethylene liner, and then add 25 mL of tetrahydrofuran and water in a volume ratio of 1:1. After stirring the mixed solution at room temperature for 3 h, the polytetrafluoroethylene liner containing the mixed solution is loaded into an autoclave, which is then placed in a 120 ℃ oven for reaction for 24 h. After the reaction is completed, the obtained product is left to volatilize at room temperature for 24 h, and then is placed in a 80 ℃ vacuum drying box for drying for 24 h to obtain a bifunctional polymer-based ammonia adsorbent, which is recorded as adsorbent C.

[0048] Example 4

[0049] Take vinyl imidazole (0.06 mol, 5.70 g) and 3-chloro-1-propanol (0.09 mol, 8.68 g) into a flask, and add 50 mL of N,N-dimethylformamide. Under the protection of inert gas Ar, the temperature is raised to 70 ℃ and stirring is performed for 48 h. After the reaction is completed, the obtained mixture is washed with diethyl ether for 5 times to remove unreacted raw materials. Finally, the washed product is placed in a 80 ℃ vacuum drying box for drying for 24 h to obtain [Hpro-Vim][Cl].

[0050] Take [Hpro-Vim][Cl] (0.015 mol, 2.83 g) and NiCl2 (0.045 mol, 15.55 g) into a flask, and add 50 mL of ethanol, and react at 80 ℃ for 2 h. After the reaction is completed, the product is subjected to rotary evaporation at 60 ℃, and then the rotary evaporated product is placed in a 80 ℃ vacuum drying box for drying for 24 h to obtain the product [Hpro-Vim][Ni3Cl7].

[0051] Take [Hpro-Vim][Ni3Cl7] 4 g, divinylbenzene 3 g, azobisisobutyronitrile 0.07 g into a polytetrafluoroethylene liner, and add 25 mL of tetrahydrofuran and water in a volume ratio of 1:1. After stirring the mixed solution at room temperature for 3 h, the polytetrafluoroethylene liner containing the mixed solution is loaded into an autoclave, which is then placed in a 120 ℃ oven for reaction for 24 h. After the reaction is completed, the obtained product is left to volatilize at room temperature for 24 h, and then is placed in a 80 ℃ vacuum drying box for drying for 24 h to obtain a bifunctional polymer-based ammonia adsorbent, which is recorded as adsorbent D.

[0052] Example 5

[0053] Into a flask, 3-chloro-1-propanol (0.09 mol, 8.68 g) and vinyl imidazole (0.06 mol, 5.70 g) were added with 90 mL of N,N-dimethylformamide. The reaction was stirred at 60 °C for 48 h under Ar atmosphere. After the reaction, the mixture was washed with ether for 5 times to remove the unreacted starting materials. The washed product was dried in a vacuum oven at 80 °C for 24 h to obtain [Hpro-Vim][CI].

[0054] Into a flask, [Hpro-Vim][CI] (0.04 mol, 7.55 g) and CuCI2(0.04 mol, 5.38 g) were added with 30 mL of ethanol. The reaction was stirred at 80 °C for 2 h. After the reaction, the product was rotary evaporated at 60 °C, and then the rotary evaporated product was dried in a vacuum oven at 80 °C for 24 h to obtain [Hpro-Vim][CuCI3].

[0055] Into a PTFE liner, 4 g of [Hpro-Vim][CuCI3], 3 g of divinyl benzene, and 0.07 g of azobisisobutyronitrile were added with 25 mL of tetrahydrofuran and water (1:1 by volume). The mixture was stirred at room temperature for 3 h, and then the PTFE liner containing the mixture was put into an autoclave, which was then placed in an oven at 120 °C for 24 h. After the reaction, the product was left to volatilize at room temperature for 24 h, and then dried in a vacuum oven at 80 °C for 24 h to obtain a bifunctional polymer-based ammonia adsorbent, which was denoted as adsorbent E.

[0056] Example 6

[0057] Into a flask, 3-chloropropionic acid (0.075 mol, 8.22 g) and vinyl imidazole (0.05 mol, 4.81 g) were added with 50 mL of N,N-dimethylformamide. The reaction was stirred at 70 °C for 48 h under Ar atmosphere. After the reaction, the mixture was washed with ether for 5 times to remove the unreacted starting materials. The washed product was dried in a vacuum oven at 80 °C for 24 h to obtain [CPA-Vim][CI].

[0058] Into a flask, [CPA-Vim][CI] (0.015 mol, 3.04 g) and NiCI2(0.045 mol, 6.27 g) were added with 30 mL of ethanol. The reaction was stirred at 80 °C for 2 h. After the reaction, the product was rotary evaporated at 60 °C, and then the rotary evaporated product was dried in a vacuum oven at 80 °C for 24 h to obtain [CPA-Vim][Ni3CI7].

[0059] [CPA-Vim][Ni3Cl7] 4 g, divinylbenzene 3 g, azobisisobutyronitrile 0.07 g were taken in a Teflon liner, 25 mL of tetrahydrofuran and water in a volume ratio of 1:1 was added. The mixed solution was stirred at room temperature for 3 h, then the Teflon liner containing the mixed solution was loaded into an autoclave, and then it was placed in a 120 °C oven for 24 h. After the reaction was completed, the obtained product was placed at room temperature for volatilization for 24 h, and finally it was placed in a 80 °C vacuum drying oven for drying for 24 h to obtain a bifunctional polymer-based ammonia adsorbent, which was recorded as adsorbent F.

[0060] Example 7

[0061] Vinylimidazole (0.05 mol, 4.81 g) and 3-chloropropylamine hydrochloride (0.06 mol, 7.96 g) were weighed into a flask, and the temperature was raised to 70 °C under the protection of inert gas Ar and stirred for 48 h. After the reaction was completed, the obtained mixture was washed with diethyl ether for 5 times to remove the unreacted raw materials. Finally, the washed product was placed in a 80 °C vacuum drying oven for drying for 24 h to obtain [Chpy-Vim][Cl].

[0062] [Chpy-Vim][Cl] (0.015 mol, 3.36 g) and FeCl2 (0.045 mol, 5.70 g) were taken in a flask, 50 mL of ethanol was added, and the reaction was carried out at 80 °C for 2 h. After the reaction was completed, the product was rotary evaporated at 60 °C, and then the rotary evaporated product was placed in a 80 °C vacuum drying oven for drying for 24 h to obtain the product [Chpy-Vim][Fe3Cl7].

[0063] [Chpy-Vim][Fe3Cl7] 4 g, divinylbenzene 3 g, azobisisobutyronitrile 0.06 g were taken in a Teflon liner, 25 mL of tetrahydrofuran and water in a volume ratio of 1:1 was added. The mixed solution was stirred at room temperature for 3 h, then the Teflon liner containing the mixed solution was loaded into an autoclave, and then it was placed in a 120 °C oven for 24 h. After the reaction was completed, the obtained product was placed at room temperature for volatilization for 24 h, and finally it was placed in a 80 °C vacuum drying oven for drying for 24 h to obtain a bifunctional polymer-based ammonia adsorbent, which was recorded as adsorbent G.

[0064] Comparative Example 1

[0065] Into a flask, 3-chloropropylamine hydrochloride (0.06 mol, 7.96 g) and vinyl imidazole (0.05 mol, 4.81 g) were weighed and 50 mL of N,N-dimethylformamide was added. The reaction was stirred at 70 °C for 48 h under Ar atmosphere. After the reaction, the mixture was washed with diethyl ether for 5 times to remove the unreacted raw materials. The washed product was dried in a vacuum oven at 80 °C for 24 h to obtain [Chpy-Vim][CI].

[0066] Into a Teflon liner, 4 g of [Chpy-Vim][CI], 3 g of divinyl benzene, and 0.06 g of azobisisobutyronitrile were added, and 25 mL of tetrahydrofuran and water (1:1 by volume) was added. The mixture was stirred at room temperature for 3 h, and then the Teflon liner containing the mixture was loaded into an autoclave, which was then placed in an oven at 120 °C for 24 h. After the reaction, the product was left to volatilize at room temperature for 24 h, and then dried in a vacuum oven at 80 °C for 24 h to obtain an ammonia adsorbent, which was denoted as Comparative Sample H.

[0067] Comparative Sample 2

[0068] Into a flask, 3-chloropropylamine hydrochloride (0.06 mol, 7.96 g) and vinyl imidazole (0.05 mol, 4.81 g) were weighed and 50 mL of N,N-dimethylformamide was added. The reaction was stirred at 70 °C for 48 h under Ar atmosphere. After the reaction, the mixture was washed with diethyl ether for 5 times to remove the unreacted raw materials. The washed product was dried in a vacuum oven at 80 °C for 24 h to obtain [Chpy-Vim][CI].

[0069] Into a Teflon liner, 4 g of [Chpy-Vim][CI], 3 g of divinyl benzene, and 0.06 g of azobisisobutyronitrile were added, and 25 mL of tetrahydrofuran and water (1:1 by volume) was added. The mixture was stirred at room temperature for 3 h, and then the Teflon liner containing the mixture was loaded into an autoclave, which was then placed in an oven at 120 °C for 24 h. After the reaction, the product was left to volatilize at room temperature for 24 h, and then dried in a vacuum oven at 80 °C for 24 h to obtain an ammonia adsorbent, which was denoted as Comparative Sample H.

[0070] Comparative Sample 3

[0071] Into a flask, 0.05 mol of vinyl imidazole (4.81 g) and 0.075 mol of 3-chloropropionic acid (8.22 g) were added with 50 mL of N,N-dimethylformamide. The reaction was stirred at 70 ℃ for 48 h under Ar protection. After the reaction, the mixture was washed with ether for 5 times to remove the unreacted raw materials. The washed product was finally dried in a vacuum oven at 80 ℃ for 24 h to obtain [CPA-Vim][Cl].

[0072] Into a PTFE liner, 4 g of [CPA-Vim][Cl], 3 g of divinylbenzene and 0.07 g of azobisisobutyronitrile were added, and 25 mL of tetrahydrofuran and water (1:1 by volume) were added. After the mixed solution was stirred at room temperature for 3 h, the PTFE liner containing the mixed solution was loaded into an autoclave, and then the autoclave was placed in a 120 ℃ oven for reaction for 24 h. After the reaction, the product was left to volatilize at room temperature for 24 h, and then was dried in a vacuum oven at 80 ℃ for 24 h to obtain an ammonia adsorbent, which was denoted as Comparative Sample J.

[0073] Test of ammonia adsorption performance:

[0074] About 0.1 g of the adsorbent was loaded into a U-shaped glass tube. At 25 ℃, ammonia gas with different concentrations was introduced into the glass tube, and the components of the outlet gas were monitored in real time by GC-MS.

[0075] Test of cycle performance:

[0076] About 0.1 g of the adsorbent was loaded into an adsorption cell, and ammonia gas was introduced at 40 ℃. After the adsorbent reached ammonia adsorption equilibrium, the ammonia adsorption capacity of the adsorbent at 1 bar was calculated. Then, the sample saturated with adsorption was kept at 120 ℃ and 0 kPa for 2 h to complete desorption. The whole adsorption-desorption process was repeated for several times, and the ammonia adsorption capacity of each time was calculated.

[0077] Figure 1 SEM images of the adsorbent B (1) obtained in Example 2 and the adsorbent D (2) obtained in Example 4. As can be seen from the images, the adsorbents B and D have rich pore channels.

[0078] Table 1: Results of N2 adsorption-desorption experiments of the adsorbents

[0079]

[0080] Table 1 further proves that the obtained bifunctional polymer-based ammonia adsorbent has certain nanopore channels.

[0081] Table 2: Ammonia adsorption capacity of the adsorbents at 25 ℃ (mol / kg)

[0082]

[0083] Table 2 shows that the bifunctional polymer-based ammonia adsorbent obtained by the present application has a high adsorption capacity for ammonia, and has a significant advantage in the adsorption capacity for low-concentration ammonia.

[0084] Figure 2 The selective adsorption curve of the adsorbent B obtained in Example 2 for a ternary mixed gas (3 vol. ammonia / nitrogen / hydrogen) at 25°C. As can be seen from the figure, as the mixed gas is passed in, the nitrogen and hydrogen instantaneously penetrate to reach adsorption equilibrium, and the adsorbent exhibits excellent selective adsorption capacity for ammonia.

[0085] Figure 3 The ammonia cycle performance test results of the adsorbent B obtained in Example 2 at 40°C, 1 bar. It can be seen from the figure that after ten cycles, the ammonia adsorption capacity of the adsorbent B is basically not lost, indicating that it has good cycle performance. Figure 3

[0086] The above only describes the preferred embodiments of the present application, and any equivalent changes and modifications made within the scope of the patent application of the present application shall be included in the scope of the present application.​

Claims

1. A method for preparing a bifunctional polymer-based ammonia adsorbent, characterized in that, Includes the following steps: 1) Mix vinylimidazole with functionalized haloalkanes, then add organic solvent a, and under inert gas protection, reflux the reaction. After that, wash the mixture with organic solvent b, and then dry the washed product to obtain intermediate product 1. 2) Mix intermediate product 1 with metal chloride, add organic solvent c to react, and then rotary evaporate the resulting reaction solution at a certain temperature. Dry the product after rotary evaporation to obtain intermediate product 2. 3) Intermediate product 2 was mixed with divinylbenzene and azobisisobutyronitrile, and an aqueous solution of tetrahydrofuran was added. After stirring at room temperature for a certain period of time, a polytetrafluoroethylene liner containing the mixed solution was placed in a hydrothermal reactor and placed in an oven for reaction at a certain temperature. After the reaction was completed, the resulting product was allowed to evaporate at room temperature, and then dried to obtain a bifunctional polymer-based ammonia adsorbent with a porous structure. Its chemical structural formula is as follows: ， Wherein, X is one of YCl3, Y2Cl5, and Y3Cl7; Y is one of Co, Ni, Zn, Fe, Mn, Mg, Ca, Sn, and Cu; and R is OH or NH3. + Cl − One of COOH; a≥10, b≥10.

2. The preparation method of the bifunctional polymer-based ammonia adsorbent according to claim 1, characterized in that: In step 1), the molar ratio of vinylimidazole to functionalized halogenated hydrocarbon is 1:0.5~4; the functionalized halogenated hydrocarbon is one of 3-chloro-1-propanol, 3-chloropropylamine hydrochloride, and 3-chloropropionic acid; the organic solvent a is one of N,N-dimethylformamide, toluene, and acetonitrile; the reaction temperature is 60~150 °C, and the time is 12~60 h; the organic solvent b is diethyl ether or ethyl acetate; the drying temperature is 20~120 °C, and the time is 12~60 h.

3. The preparation method of the bifunctional polymer-based ammonia adsorbent according to claim 1, characterized in that: In step 2), the molar ratio of intermediate product 1 to metal chloride is 1:0.5~6; the metal chloride is one of CoCl2, CaCl2, MgCl2, ZnCl2, NiCl2, SnCl2, CuCl2, MnCl2, and FeCl2; the organic solvent c is one of ethanol, dimethyl sulfoxide, and methanol; the reaction temperature is 60~80 ℃, and the time is 2~12 h; the rotary evaporation temperature is 30~80 ℃; and the drying temperature is 60~120 ℃, and the time is 12~60 h.

4. The preparation method of the bifunctional polymer-based ammonia adsorbent according to claim 1, characterized in that: In step 3), the mass ratio of intermediate product 2, divinylbenzene, and azobisisobutyronitrile is 1:(0.5~5):(0.005~0.2); the volume ratio of tetrahydrofuran to water in the aqueous solution of tetrahydrofuran is 1:1; the stirring time at room temperature is 1~5 h; the reaction temperature is 80~160 ℃ and the time is 12~48 h; the volatilization time is 12~48 h; and the drying temperature is 40~120 ℃ and the time is 12~60 h.

5. The application of a bifunctional polymer-based ammonia adsorbent prepared by the method described in claim 1 in the adsorption and separation of low-concentration ammonia.

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